The freeing of frozen loads of waste in the roll-off boxes now much used for compacting trash at retail installations has long been a problem despite the efforts of various patentees to provide cable pulled ejector bars which move along the bottom of the box to urge the load rearwardly. In my above mentioned patent application, not only does the tilting of the roll-off box on its tilt bed vehicle, apply tremendous tension on an ejector bar but extension cables anchored on the roof of the box and encompassing the front of the frozen load also must be tautened and pulled to squeeze and compress the load away from adherence to the front and side walls of the box.
The ejector bar devices of the prior art such as in U.S. Pat. No. 3,626,648 to Pioch of Dec. 7, 1971 and the device of my said patent application thus must have at least one sheave which will withstand the pull on the cable without breakage of the sides of the cable groove or of other parts of the sheave.
It has been found that commercially available sheaves are not satisfactory for the purpose and that the machining of a sheave of suitable dimensions from a solid steel block is too costly to be practical. It will also be understood that certain users of roll-off boxes may seek to substitute replacement sheaves of less cost and strength in instant load release systems of my invention, thereby encountering sheave abrasion, breakage failure, etc. to the detriment of the system.